We use calibration studies quite a lot in my field. Extrapolations to the high or low end of the linearity curve are dangerous practices. Still, I've never seen a curve go flat at the last calibration point. Perhaps a simple recalibration with a greater range of standards would make this all go away.

1. "Testimony offered at the hearing showed the manufacturer of the Intoxilyzer failed to follow state rules requiring the solutions used to calibrate the breath machines be certified by an independent lab."

That's a big deal. Total sixth amendment violation.

2. ""If you're calibrating from 0.05 to 0.15 and did these three points, you have the correlation coefficient, you've proven to me that your instrument works -- definitely works between 0.05 percent and 0.15 percent. There's no data to say that it works at 0.16 percent. There's no data to say it works at 0.04 percent," Lee N. Polite, an expert in organic chemistry, testified."

This is absurd, but I understand where it came from. The state has to prove the science works. If the defense suggests that it's possible the science doesn't work and the state has no rebuttal (i.e., "the instrument works at much higher BACs but that it's not calibrated beyond .16 mg/mL because the statute doesn't distinguish between .16 and .61.") then the prosecutor hasn't met his burden and the charge should rightfully go away. The state can't presume that the instrument works beyond the range where it can be tested, even if a reasonable person would expect that the device would work just fine. Something - anything - that could prove an instrument calibrated to .05-.15 could correctly detect a BAC over .15 and report it as same would've saved the day here.

Breathalyzer does not measure alcohol, it measures the brightness of light of various colors (wavelengths.) The computer then uses a secret formula to convert the color measurements into a blood alcohol number. The formula is a trade secret and so you can't really fight the validity of the machine.

Imagine if the defense attorney used an "electron bullshiat detector" to discredit the officer's testimony and then refused to tell the prosecutor how it works... and now also imagine that the judge is OK with that.

TheWhoppah:Breathalyzer does not measure alcohol, it measures the brightness of light of various colors (wavelengths.) The computer then uses a secret formula to convert the color measurements into a blood alcohol number. The formula is a trade secret and so you can't really fight the validity of the machine.

Um, what you just described is called a 'spectrometer', which is generally used to measure *the components of a substance*.

What you just said amounts to "Meter stick does not measure distance. It measure the number of notches along a stick of wood."

/Now, Breathlyzers should not get a pass and sure as fark should not be treated as magic black boxes, and should absolutely always be A) Followed with a blood test, and B) proven to have been F*CKING calibrated recently.

Pffft. Just make a law that takes the court out of any Breathalyzer case.

British Columbia tried that. Instant 30 minute roadside conviction by the officer(abuse of power that was not his to use). Big fine. Perp blocked from accessing the courts to challenge the questionable reading from the screening tool handheld breathalyser. All found to be a total violation of the constitution(charter of rights) about not blocking access to the courts, along with other things. 50 million dollars from fines from 10 months of the injustice, that the government is refusing to refund.Alberta was looking to implement it as well, for the big cost savings. In BC challenge cases were taking 3 years to get to court at which point the occasional Judge was throwing out the charges due to delay of due process.'Monopoly vehicle insurance company' also penalized drivers because you can't get car insurance or drivers license anywhere else.

Handheld breathalysers are only meant as a screening device(they have an expiry date as well). If it reads at above a certain number or twinkling light, the driver is to be taken to the station to use the climate controlled unit for official court admissible reading.

/Drunk Driving: Still a misdemeanor in many places and no need to worry about being actually incarcerated for longer than 2 hours for each offense.//Smoke one joint on your front porch in certain States? 2 years in jail.///An automatic 3 year sentence for carrying someone elses gun? Unconstitutional, due to no weighing of the merits of conditions of the crime.

mrlewish:Simple translation: The machines are not accurate past a certain BAC so charges that come with those higher BAC can't be brought.

I would be surprised if that was quite true. They used to issue tickets before the machines were available, for instance. It's just harder to prove. And, if the police are aware of this ruling (and they for sure will be), they can always do a visual documentation of erratic driving and charge you with reckless separate and apart from DUI.

Flakeloaf:This is absurd, but I understand where it came from. The state has to prove the science works. If the defense suggests that it's possible the science doesn't work and the state has no rebuttal (i.e., "the instrument works at much higher BACs but that it's not calibrated beyond .16 mg/mL because the statute doesn't distinguish between .16 and .61.") then the prosecutor hasn't met his burden and the charge should rightfully go away. The state can't presume that the instrument works beyond the range where it can be tested, even if a reasonable person would expect that the device would work just fine. Something - anything - that could prove an instrument calibrated to .05-.15 could correctly detect a BAC over .15 and report it as same would've saved the day here.

Gaius:If .15 is the threshold where a more serious charge is levied, and they have proven the device is accurate to at least .15, then it would seem that the device's accuracy beyond .15 is a moot point.

BradleyUffner:Gaius: If .15 is the threshold where a more serious charge is levied, and they have proven the device is accurate to at least .15, then it would seem that the device's accuracy beyond .15 is a moot point.

A system to sample the breath of the suspectTwo glass vials containing the chemical reaction mixtureA system of photocells connected to a meter to measure the color change associated with the chemical reaction

To measure alcohol, a suspect breathes into the device. The breath sample is bubbled in one vial through a mixture of sulfuric acid, potassium dichromate, silver nitrate and water. The principle of the measurement is based on the following chemical reaction:

In this reaction:

The sulfuric acid removes the alcohol from the air into a liquid solution.

The silver nitrate is a catalyst, a substance that makes a reaction go faster without participating in it. The sulfuric acid, in addition to removing the alcohol from the air, also might provide the acidic condition needed for this reaction.

During this reaction, the reddish-orange dichromate ion changes color to the green chromium ion when it reacts with the alcohol; the degree of the color change is directly related to the level of alcohol in the expelled air. To determine the amount of alcohol in that air, the reacted mixture is compared to a vial of unreacted mixture in the photocell system, which produces an electric current that causes the needle in the meter to move from its resting place. The operator then rotates a knob to bring the needle back to the resting place and reads the level of alcohol from the knob -- the more the operator must turn the knob to return it to rest, the greater the level of alcohol.

If the machine is only tested at .05, .10 and .15, how do we know that a software error isn't making .04 read as .06 and resulting in a false positive (assuming a .05 threshhold; varies by state)? And the calibration standards not being proper? This would seem to call into question all readings from the machine, not just those of .16 or higher.

Satanic_Hamster:Flakeloaf: This is absurd, but I understand where it came from. The state has to prove the science works. If the defense suggests that it's possible the science doesn't work and the state has no rebuttal (i.e., "the instrument works at much higher BACs but that it's not calibrated beyond .16 mg/mL because the statute doesn't distinguish between .16 and .61.") then the prosecutor hasn't met his burden and the charge should rightfully go away. The state can't presume that the instrument works beyond the range where it can be tested, even if a reasonable person would expect that the device would work just fine. Something - anything - that could prove an instrument calibrated to .05-.15 could correctly detect a BAC over .15 and report it as same would've saved the day here.

But couldn't you still prove that his BAC was at least 0.15?

No. The court cannot presume that a scientific process that functions a certain way when the sample is .15000 will work exactly the same way when the reading is .15001, nor can it extrapolate science to draw conclusions that meet the burden of reasonable doubt when it is possible for these things to be proven directly and introduced as evidence. The prosecution did not do this, so they did not meet their burden.

Flakeloaf:2. ""If you're calibrating from 0.05 to 0.15 and did these three points, you have the correlation coefficient, you've proven to me that your instrument works -- definitely works between 0.05 percent and 0.15 percent. There's no data to say that it works at 0.16 percent. There's no data to say it works at 0.04 percent," Lee N. Polite, an expert in organic chemistry, testified."

This is absurd, but I understand where it came from. The state has to prove the science works. If the defense suggests that it's possible the science doesn't work and the state has no rebuttal (i.e., "the instrument works at much higher BACs but that it's not calibrated beyond .16 mg/mL because the statute doesn't distinguish between .16 and .61.") then the prosecutor hasn't met his burden and the charge should rightfully go away. The state can't presume that the instrument works beyond the range where it can be tested, even if a reasonable person would expect that the device would work just fine. Something - anything - that could prove an instrument calibrated to .05-.15 could correctly detect a BAC over .15 and report it as same would've saved the day here.

From a mathematical viewpoint, it's not absurd at all. Interpolation is quite different from extrapolation. As a very simple example, if you used a high order polynomial to interpolate between a few data points, you might get great accuracy within that range. But if you tried to extrapolate, the curve would blow up right outside that range and be useless. Now again, that's very simple, but you'd be surprised by how much polynomial fitting you see in code because that's what programmers know.

The machine's not accurate over .15? That's ridiculous, considering the number of people who get popped for DUI with BACs in the .15-.30 range. Heck, .15 used to be the upper limit in lots of states up until about 1980 because it's where, for most people, driving starts becoming visibly erratic in a way that's trivially observable by a patrol officer. (Risk of a collision due to eroded reaction time and impaired judgment, of course, increases with any alcohol consumption at all. Just where that risk rises to a level where one "shouldn't drive," or where it should be subject to criminal sanction, is open to debate.)

And ... if you're going to rely on a machine for evidence, you have to prove that the machine is accurate and working properly. If you can't, the evidence is usually inadmissible. That's the way the system is supposed to work.

I don't like drunk drivers either but in a free society the prevailing ethic is supposed to be that it's better for guilty people to go free than for innocent people to get punished.

Felgraf:TheWhoppah: Breathalyzer does not measure alcohol, it measures the brightness of light of various colors (wavelengths.) The computer then uses a secret formula to convert the color measurements into a blood alcohol number. The formula is a trade secret and so you can't really fight the validity of the machine.

Um, what you just described is called a 'spectrometer', which is generally used to measure *the components of a substance*.

What you just said amounts to "Meter stick does not measure distance. It measure the number of notches along a stick of wood."

The semantics are important. Scientific tests describe what they measure, not the inferences drawn from the test. When diabetics prick their finger, they are performing a "Blood-Sugar Test" not a "Diabetes Test." The Intoxilyzer has a misleading name that infers a test of intoxication... which is false. The machine measures the brightness of light, from which it uses a secret formula to estimate a blood-alcohol level, from which the law infers intoxication and therefore an impaired ability to operate a motor vehicle. This process would not pass scientific muster as an intoxication test or as a test for operating a motor vehicle and yet the words used to describe the test make it seem much more valid than is reasonably justified by a test that measures the brightness of light.